Chapter 8

1. Chapter 8 Electron Configuration, Periodicity, and Properties of the Elements Dr. S. M. Condren

2. Electromagnetic Radiation Electromagnetic wave • A wave of energy having a frequency within the electromagnetic spectrum and propagated as a periodic disturbance of the electromagnetic field when an electric charge oscillates or accelerates. Dr. S. M. Condren

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4. Electromagnetic Radiation Electromagnetic wave • wavelength • frequency • amplitude Dr. S. M. Condren

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6. Quantum Mechanics Quantum theory • the theory of the structure and behavior of atoms and molecules. Dr. S. M. Condren

7. Black Body Radiation http://www.cbu.edu/~mcondren/C11599/BBvis.mov Dr. S. M. Condren

8. Electromagnetic Radiation nl= c where n => frequency l => wavelength c => speed of light Dr. S. M. Condren

9. Electromagnetic Radiation Ehi - Elo = hc/l where E => energy h => Planck's constant c => speed of light l => wavelength Dr. S. M. Condren

10. Photoelectric Effect • the emission of electrons by substances, especially metals, when light falls on their surfaces. Dr. S. M. Condren

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12. Photons The quantum of electromagnetic energy, generally regarded as a discrete particle having zero mass, no electric charge, and an indefinitely long lifetime. Dr. S. M. Condren

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14. Line Spectrum A spectrum produced by a luminous gas or vapor and appearing as distinct lines characteristic of the various elements constituting the gas. Dr. S. M. Condren

15. Emission Spectrum The spectrum of bright lines, bands, or continuous radiation characteristic of and determined by a specific emitting substance subjected to a specific kind of excitation. Dr. S. M. Condren

16. Ground State The state of least possible energy in a physical system, as of elementary particles. Also called ground level. Dr. S. M. Condren

17. Excited State Being at an energy level higher than the ground state. Dr. S. M. Condren

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19. Absorption Spectrum • Light shinning on a sample causes electrons to be excited from the ground state to an excited state • wavelengths of that energy are removed from transmitted spectra Dr. S. M. Condren

20. Knowing diamond is transparent, which curve best represents the absorption spectrum of diamond (see below)? A, B, C Dr. S. M. Condren

21. The Atomic Spectrum of Hydrogen and the Bohr Model Bohr Model for the Hydrogen Atom mnr = nh/2p Dr. S. M. Condren

22. Bohr Model Netscape • NCSU Materials Science site • Chapter 2 Atomic Bonding • I Atoms and Electrons • slide 2 or • http://odin.cbu.edu/~mcondren/bohr.html or through the CHEM 115 homepage Dr. S. M. Condren

23. Bohr Atom Dr. S. M. Condren

24. Bohr Model E = -B/n2 where n => quantum number 1, 2, 3, 4, 5, 6, 7, etc Dr. S. M. Condren

25. Bohr Model E = (-2.179 X 10-18 J/part.) (6.022 X 1023 part./mole) (1 kJ/103 J)/n2 = (-1312 kJ/mol)(1/n2) Dr. S. M. Condren

26. Bohr Model for hydrogen ground state: n = 1 excited state: n > 1 Dr. S. M. Condren

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28. Line Spectra Lyman series => ultraviolet n > 1 ==> n = 1 Balmer series => visible light n > 2 ==> n = 2 Paschen series => infrared n > 3 ==> n = 3 Dr. S. M. Condren

29. Line Spectra See CHEMWORKS software Dr. S. M. Condren

30. According to the energy diagram below for the Bohr model of the hydrogen atom, if an electron jumps from E1 to E2, energy is absorbed emitted not involved Dr. S. M. Condren

31. Heisenberg, Werner1901–76, German physicist1932 Nobel Prize in physics A founder of QUANTUM MECHANICS, he is famous for his uncertainty principle, which states that it is impossible to determine both the position and momentum of a subatomic particle (such as the electron) with arbitrarily high accuracy. Dr. S. M. Condren

32. Heissenberg Uncertainty Principle “it is impossible to determine both the position and momentum of a subatomic particle (such as the electron) with arbitrarily high accuracy” The effect of this principle is to convert the laws of physics into statements about relative, instead of absolute, certainties. Dr. S. M. Condren

33. Orbitals • region of probability of finding an electron around the nucleus • 4 types => s p d f • maximum of 2 electrons per orbital Dr. S. M. Condren

34. Pure Atomic Orbitals shape # of orbitals / energy level s spherical 1 p dumbbell 3 d complex 5 f very complex 7 Dr. S. M. Condren

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36. Shapes of Orbitals http://www.colby.edu/chemistry/OChem/DEMOS/Orbitals.html Dr. S. M. Condren

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41. Electronic Configurations • The shorthand representation of the occupancy of the energy levels (shells and subshells) of an atom by electrons. Dr. S. M. Condren

42. Electronic Configuration shells => energy levels subshells => orbitals Dr. S. M. Condren

43. Electron Filling Order Diagram 1s 2s 2p 3s 3p 3d 4s 4p 4d 4f 5s 5p 5d 5f 6s 6p 6d 7s Dr. S. M. Condren

44. Electronic Configuration H atom 1 electron 1s1 Dr. S. M. Condren

45. Electronic Configuration He atom 2 electrons 1s2 Dr. S. M. Condren

46. Electronic Configuration Li atom 3 electrons 1s2, 2s1 Dr. S. M. Condren

47. Electronic Configuration Cl atom 17 electrons 1s2, 2s2, 2p6, 3s2, 3p5 Dr. S. M. Condren

48. Electronic Configuration As atom 33 electons 1s2, 2s2, 2p6, 3s2, 3p6, 4s2, 3d10, 4p3 or [Ar] 4s2, 3d10, 4p3 Dr. S. M. Condren

49. Mn: [Ar]4s2 3d? How many d electrons does Mn have? 4, 5, 6 Dr. S. M. Condren

50. Electronic Configuration negative ions add electron(s), 1 electron for each negative charge Dr. S. M. Condren